Excavator crane



Qct 1931- H. L. MITCHELL ET AL 1,829,569

EXCAVATQR CRANE Filed Feb. 21, 192": '4 Sheets-Shee l INVENTOR.

W/{W BY M M M ATTORNEYS.

Oct. 27, *1931. H. MITCHELL ET AL EXCAVATOR CRANE I Filed Feb. 21. 1927 4 Sheets-Shee 2 'nvmvroa 751521.,

g4 BY I a M M M ATTORNEYS.

@c' c, 27, 1931. H. MITCHELL ET AL 1,829,559

EXCAVATOR CRANE Filed Feb. 21, 1927 4 Sheets-Shee 3 1 N V EN TOR. K A TTORNEYS- H. L. MITCHELL ET AL Get. 27, 1931.

EXCAVATOR CRANE Filed Feb. 21, 1927 4 Sheets-Shee 4 B a wm S Nv NR E. Q bk OW V g a r U K UN 3. \N. E. .nm mm R v Q wm a 3 W mm Q mw INVENTOR. (W BY g E ATTORNEYS.

Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE HOLGER L. MITCHELL AND ROLF IJUNGKULL, OF MILWAUKEE, WISCONSIN, ASSIGNOBS TO EARNISCHFEGER CORPORATION, OF MILWAUKEE, WISCONSIN, A. CORPORATION OF WISCONSIN EXGAVATORY 01mm Application filed. February 21, 1927. Serial No. 169,703.

This invention relates to excavator cranes, and although well adapted for embodiment in a power shovel the excavator crane is also adapted for universal use and may be 5 equipped with various attachments such as the clam-shell bucket, drag-line bucket, power-hoe or the like.

One of the objects of the invention is to provide an excavator crane of this character wherein the operating and controlling elements are so consolidated and organized as to be well adapted to be mounted on the small platform of the so-called truck type of machine or in connection with other machines where the platform space is limited.

In carryingout the invention in a power shovel the digging and hoisting drums are mounted on a single shaft which may be constantly rotated in one direction by an internal combustion engine or other prime mover mounted on the platform; The boom hoist drum may also be mounted on the same shaft.

The several drums are selectively driven and controlled in either direction on and from the shaft to carry out the operation of the crowding mechanism whereby the dipper stick is advanced or retracted, to operate. the hoist line whereby the dipper stick is elevated or lowered, and to operate the boom hoist line whereby the boom itself is bodily raised or lowered. In conjunction with the multiple drum assembly on the single shaft the invention also proposes a novel double chain driven through the boom foot and centrally of the boom, whereby the crowding mechanism may be operated and controlled in any adjustment of the boom without any alteration or adjustment of the crowding mechanism drive. with the advantage of a chain drive and in an organization wherein overhung gears or overhung drives are eliminated, the chain drive along the boom being-centrally thereof or intermediate the bearings of the shipper shaft and the bearings of the axis of the boom foot. The consolidation of the several drumson the one shaft is had in an organization employing planetary gears to rotate at least several of the drums in one direct-ion Th' (1 t l h 1 1S a Van age 15 ad a ing the pawl and ratchet arrangement for and clutches for fixing the drums to the shaft for rotation in the other direction.

Another object resides inthe provision of an excavator crane of this character which is of simple and durable construction, which is reliable and effective in operation, which embodies means for tensioning the chains of the double chain shipper shaft drive and which is adapted to be manufactured at a comparatively slight expense from materials and by means of facilities ordinarily available.

Other objects and advantages reside in certain 'novel features of the construction, arrangement and combination of parts which will be hereinafter more fully described and particularly pointed out in the appended claims, reference being had to the accompanying drawings forming a part of this specification, and in which:

Figure 1 is a view in side elevation showing an excavator crane embodying the present invention.

Figure 2 is a fragmentary plan view showing the drum assembly on the platform and the double chain shipper shaft drive, parts being omitted for the'sake of illustration.

Figure 3 is a view in side elevation of the parts shown in Figure 2.

Figure 4 is a fragmentary view illustrating the reeving of the boom hoist line.

Figure 5 is a diagrammatic perspective view further illustrating this feature.

Figure 6 is a view partly in elevation and partly in section on line 6-6 of Figure 2 and illustrating the multiple drum assembly on the single shaft.

Figure 7 is a sectional view on line 7-7 of Figure 3; and,

Figure 8 is a diagrammatic view illustratpreventing the boom hoist drum from over- {junning the shaft during the lowering of the Referring to the drawings the numeral 1 desi ates a truck which has self-laying trac 2 mounted and 'driven. in the usual manner. On this truck 1 a platform 3 is mounted and supported, the latform 3 being adjustable or swingable in a orizontal plane about a vertical axis associated therewith and 55 ring gear .33- to swing with the truck 1. At the forward end of the platform 3 a boom foot socket 4 is secured and in this socket 4 a boom foot 5 in the form of a yoke is rotatably fitted. The boom foot -5 is rigidly secured to the lower end of the boom' 6. A fixed pin or shaft 7 extends through alined bearings provided in the boom foot socket 4 and in the boom foot 5 to con-' strain the boom to swinging movement in a vertical plane and about the horizontal axis afforded by the stationary pin or shaft 7. This boom 6 is braced laterally by braces 8 connected with the boom as at 9 and having links 10 connecting the lower ends of the braces to the platform 3. One pivotal axis of each link 10 1s transversely aligned with the fixed shaft 7 so that the braces 8-do not interfere with the vertical movement of the boom and yet brace the same laterally.

A dipper stick 11 is provided and carries a bucket or scoop 12 in the usual manner. The dipper stick 11 is made up of a pair of members 11' which are slidably fitted in' saddles blocks or guides 13 pivotally mounted on the ends of a shipper shaft 14, rotatably support- 'ed in bearing brackets 15 fixed on the sides of the boom. Pinions 17 fixed on the shipper shaft enga e racks 18 fixed on the members 11 of the ipper stick 11 to move the dipper stick in and out and alsoto coact with the guides 13 to constrain the dipper stick to proper movement. a

An internal combustion engine 20 or other suitable prime mover is mounted on the platform 3 and has a pinion 21 fixed to its engine shaft 22' the pinion 21 meshing with a large gear wheel 23, fixed on a shaft 24 extending transversely of the platform and rotatable in suitable bearings 25 secured thereon. The angular adjustment of the platform on the truck 1 is effected and controlled from this shaft by means of a pair of clutches 26 and 27 associated with oppositely disposed beveled gear wheels 28 and 29 for selectively clutching'these gear wheels to the shaft: 24. The beveled gear wheels 28 and 29 constantlymesh with the beveled gear wheel 30 connected to avertical shaft 31 journaled in bearin provided on the platform and having a lnion 32 on its lower 1 end meshin .with a vrmg gear 33 fixed on the truck. y engaging the clutches 26 or 27 the pinion 32 may be rotated in one or the other direction and travels around the the platform 3 as may bedesirable. A sma 1 gear wheel 35 :is fixed to the'shaft 24 and meshes with a large gear wheel 36 keyed on a drum shaft 37. The

drum shaft 37 extends transverse] of the platform 3 and parallel to the sha 24 and is rotatably mounted in suitable bearings 38 provided therefore ,on the platform. It will be understood from the foregoing that this shaft 37 is continuously rotated at a constant speed in a counter clockwise direction as viewed in Figure 1 when the engine 20 is running. On thissingle drum shaft 37 all 37 adjacent one end thereof; a hoist drum 40 is loosely mounted on the shaft 37 adjacent the drum 39; and a boom hoist drum 41 is loosely mounted on the shaft 37 adjacent the hoist drum 40.

The digging drum 39 has a sprocket wheel 42 integral therewith and from this sprocket wheel the motion is taken for rotating the shipper shaft 14 in either direction to advance or thrust forward the dipper stick or to retract the same as may be desirable during the. excavating operation; In carrying out this purpose a sprocket chain 43 is engaged with the sprocket wheel 42 and is also engaged with a sprocket wheel 44 keyed on a shaft 45, journaled in bearings 46 provided at the upper ends of bracket arms 47.

The bracket arms 47 have bearing openings 48 in which the ends of the fixed shaft or pin 7 are rotatably fitted whereby the arms 47 may be adjusted to tension the chain 43. This adjustment is effected and secured by tensioning screws 49 having eyes integral therewith and pivotally connected as at 50 to bifurcated In S 51 formed on and project- 'ing forwardly rom the lower ends of the arms 47 These adjustin screws 49 extend through openings form in the platform 3 or in a art fixedto the platform and are held in ad usted position by nuts '52 threaded on the screws and engaging the opposite sides of the platform. Rearwardly' rojecting extensions 54 are provided on t e arms 47 beyond the bearings 46 and are connected by a transversely extendin tie rod 55 held in position by nuts 56.. ins 57 i or other suitable means are mounted on the ends of the shaft 7 and coact with the adjacent portions of the boom foot socket 4 to prevent axial displacement of the arms 47 on the stationary shaft or pin 7. A gear 'wheel 58 is keyed to the shaft 45 at a point spaced from the sprocket wheel 44 and this gear Wheel 58 meshes witha similar gear wheel 59 inteally formed with or suitably secured to a lll sleeve shaft 60 rotatably fitted on the stationar shaft or pin 7 between the arms of the-yo e of the boom foot. This same sleeve shaft.60 also has a sprocket wheel 61 integral- 1y formed therewith or suitably fixed thereto, and with the sprocket wheel 61 a sprocket.

chain62 meshes. The sprocket chaini62-extending centrally along the boom 6 and around a sprocket wheel 63 fixed to the portion of the sl ili gper shaft lying between its bearings 15. e upper run of this sprocket chain 62 travels over a tensioning sprocket wheel 64 adjustably mounted on a bracket 65 fixed to the boom 6 and the lower run there- .1

of travels around an idler guide sprocket 66 also mounted on the boom-6. With this arrangement it is noted that the shipper shaft has a double chain drive through the boom foot and that the drive is of such a character that sprocket chains may be employed. The drive is transmitted through and around the axis on which the boom swings so that adjustment of the boom in no way impairs shaft. When the dipper stick 11 is to be thrust forward the drum 39 is clutched to the shaft 37 to rotate inthe same'direction as the shaft 37 and at the same s eed. This clutching of the drum 39 may e brought about by means of a clutch band 67 encircling an annular flange 39 of the drum 39, one end of the band 67 being suitably connected to a spider 68 keyed to the shaft 37 along side of the drum 39, the other end of the hand 67 being connected with a contracting and expanding lever 69 having a stud 70 rotatably mounted ,on the spider 68. This lever 69 also hasa curved arm 71 extending through an opening in the spider to the opposite side thereof from the drum 39. The inner end of this arm 71 is pivotally connected to a link 72 which, in turn, is pivotally connected to 2. lug 73 integral with the hub 74 of a pulley 75. The pulley 75 is loosely mouilted on the shaft 37 but its grooved periphery is encircled by a-brake band 76 which is under the control of suitably extending and contracting means. When this brake band 76 is contracted it tends.to hold the pulley 7 5 against movement and this through the-link 7 2 rocks the lever 71 about its stud 7 0 ,and contracts the band 67 on the flange 39 of the drum 39 to clutch the drum .39 to the shaft 37 It is to,be understood that when the drum 39 is thus clutched to the shaft it is rotated bodily with the spider 68 and lever71. The

ulley slips relative,to its contracted brake band 76 but the drag exerted by the brake band on the pulley maintains the brake band 67 contracted and the drum 39 effectively clutched to the shaft 37.

For the purpose of rotating the drum 39 in an opposite direction to retract the dipper stick 11 planetary gearing is provided and is of the type shown-in prior Patent Number 1,57 0,108, granted January 19,1926, to Lewis Wehner. This planetary gearing comprises on stud shafts 79 fixed in a carrier 80, having its hub loosely mounted onthe shaft 37 and provided with a peripheral flange 81. These planet gears 78 also mesh 'with an internal ring gear 82 fixed to or otherwise-securely mounted upon the drum 39. A lanetary brake 83 is cooperatively associated with the flange 81-of the carrier and is controlled in the usual manner. With this arrangement, when the shaft 37 is turning and the planetary brake 83 is released, pinion 77 rotates the planet gears 78 which travel around the internal gear 82 and bodily rotate their carrier 80, since the carrier is unrestrained and free to rot-ate at this time. However, when the planetary brake 83 is contracted on to the flange 81 of the carrier, the carrier is held and consequently the planet gears 78 cannot move bodily but may only rotate about their studs 79. This rotation of the planet gears 78 rotates the drum 39 in a direction opposite to the rotation of the shaft 37.

In order to hold the drum 39 in any position when both the clutch and planetary gearing associated therewith are released or idle a manually operated brake 84 is operatively associated with the peripheral portion 85 of the drum 39 and may be clamped around such portion or released therefrom. Of course, the brakes 83 and 84 are anchored on the platform in a manner similar to the corresponding brakes in the patent hereinabove mentioned.

A hoist line 86 isprovided and has one end secured to and Wound around the hoist drum 40 as shown in Figure 1 and passes over a sheave 87 mounted on the boom 6 adjacent its upper and outer end. The hoist line then passes down under a sheave 88 interconnected with the outer end of the dipper stick 11 and bucket 12 as shown in Figure 1, and the hoist line then extends up to the outer end of the boom 6 and is anchored or dead ended thereon as shown at 89. The drum 40 is clutched to the shaft 37 to rotate therewith when it is desired to elevate the outer end of the dipper stick, that is, to elevate the bucket on the outer end of the dipper stick and the clutch employed for this purpose is preferably the same as the clutch heretofore described in connection with the drum 39, this clutch co- I acting with a flange 40* provided on the drum 40, and utilizing the large gear wheel 36 as its spider. The other parts of this clutch for the drum 40 correspond to similar parts of the clutch provided for the drum 39 and are designated by primed reference numerals. In order to hold the drum 40 in any adjustment it is provided with an annular flange 90 at one end thereof and with this flange 90 a brake 91 is associated, the brake being mounted on the platform and suitably controlled. When the brake 91 is released and the band 67 disengaged from the flange 40 the bucket the dippe 12 lowers under the action of gravity but this action is controlled by the brake 91. The lowering may be accelerated by releasing the clutch and brake of the drum 40 and thrusting rstick 11' outwardly by clutching the drum 39 on the shaft 37. A boom hoist line 92 is provided and has one end secured to and wound on the drum 41. The boom hoist line 92- then (passes up over a pulley 93 frotatably mounte on a shaft 94 carried at the upper end of a frame-work, 95 as shown in Figures 1', 4 and 5, The hoist line then passes forwardly and upwardly to a sheave 96 carried by a bracket. 97 mounted on the u boom,-t-raverses the boom to a sheave 98 arranged 'on the opposite side of the boom from the sheave 96 but located at the same level as the sheave 96. The boom hoist line then passes rearwardly to a sheave 99 mounted on the shaft 94, ex'tends'along the shaft 94 to a' sheave 100 also mounted thereon, then extends forwardly to sheave 101 mounted on the same axis as the sheave 96 but below the same, then extends through the boom' to a sheave 102 mounted on the same axis as the sheave 98 but disposed below the same, and

then extends rearwardly to the framing 95 to which it is anchored or dead-ended as at 103.

With the hoist line 92 wound around the.

drum 41 and reeved as shown, the drum is ing to the arts of the planetary gearing 39 ordesignat by prime reference numerals. When the boom 1s to be lowered the drum 41 is permitted rotate in the same direction as the shaft'3 that is in a counterclockwise direction as viewed in Fi 1 and this movement is controlled bya rake 105. With parts possessing the mass of the boom and the elements carried thereby it is undesirable that the lowering speed of the drum 41 should ever exceed the'speed of rotation of the shaft 37 and for this purpose a clutch arrangement isprovided between the drum 41 and the shaft 37 to revent the drum 41 from over-runnin the-s aft 37. This clutch arrangement includes a ratchet 106 keyed to the shaft 37 within the peripheral flan e 41 do .gage the pawl 107 from the ratchet 106 at the of the drum 41. A pawl 10 is pivote as at 108 to the drum 41 and coacts with the teeth of theratchet106. To automatically disenproper time whereby to prevent clicking and yet automatically engage the pawl and ratchet when engagement-is desirable spring projected friction cups or shoes 109 are carelevated when the drum 41 is rotated in a direction opposite to the shaft 37, that is,

:is a. dou

ried by the pawl 107 and enga e cheek plates- 110 fixed to the ratchet 106 and tween which the pawl 107 andishoes 109 are positioned.

With this pawland rachet arrangement when the lanetary gearing 1s o rated to rotate the um 41 in a clockwise dii ection as viewed in Figure 1, pawl 107 will be disengaged from the ratchet 106 because of the ag which the cheek plates exert on the friction shoes 109. These cheek plates 110 rotate with the ratchet 106, and shaft 37 in a counter clockwise direction and with the drum 41-rotating in a clockwise direction the shoes 109 are pulled bythe cheek plates to swin the pawl 107 away from the ratchet 106. owever, when and the bra e. released, the weight of the boom and theparts carried thereby causes the drum 41 to operate in .a-counter clockwise direction, that is in the same direction the planetar gearing 104 is not operating as the shaft. If the drum 41 rotates so fast as to tend to over-rum the shaft 37 the shoes 109 dra on the cheek plates 'to cause the pawl 10 to engage the ratchet 106 and lock the drum .41 to the shaft 37.

From the foregoing it will be understood that the present invention consolidates all of the drums on a single shaft. Such an arrangement is so compact as to be well adapted to be mounted on the platforms of thesm'all power shovels or so-called truck type.

Another important advantage resides in the organization with a single shaft carryigging drum or sprocket and a hoist mg .a drum of a sh pper shaft driveof such char acter that the driving elements are located centrally of the boom. Not only are these advantages had but the shipper shaft drive le chain drive exerted through the .axis of the boom foot in such a manner that the boom may be raised and lowered without effecting the drive for the shipper shaft. Moreover, by having the chain drive alo the boom embodyin a sprocket wheel fix to the shipper sha between the bearings hung gears are obvia The invention claimed is:

1. An excavator crane comprising a platform, "a boom pivotally mounted on the plate form, a dipper stick mounted on the boom,

crowding mechanism mounted on the boom and operatively associated with the dipper stick, a hoist hne associated with. the boom and operatively associated with the dipper stick a digging drlmi, a hoisting drum operatively connected with the hoist line, asingle shaft on which the digging drum and hoisting drum are mounted, a sleeve shaft rotatably mounted about the axis of the boom foot, means for rotating said sleeve shaft from the digging drum including a pair of bracket arms adjustably mounted on the axis of the 'boom --foot a shaft rotatably mounted on said bracket arms, a sprocket 110 thereof, the disadvanta s inherent in over- I wheel fixed to said shaft, a sprocket wheel fixed to the digging drum, a sprocket chain engaged with said sprocket wheels, means coacting with the bracket arms for tensioning the sprocket chain, gearing between the shaft mounted on the bracket arms and the sleeve shaft, and chain and sprocket gearing between the sleeve shaft and the crowding mechanism.

2. A multiple drum assembly for excavator cranes including a single drum shaft, a diging drum, a hoisting drum and a boom hoist rum, all mounted on said shaft, means for clutching the digging drum to the shaft to rotate therewith, planetary gearing for reversely rotating the digging drum from the shaft, means for clutching the hoisting drum to the shaft, means for clutching the boom hoisting drum to the shaft, and planetary gearing for reversely rotating the boom hoisting drum from the shaft.

3. An excavator crane comprising a platform having a boom foot socket, a boom having a foot, a shaft pivotally connecting the boom to the boom foot socket, a shipper shaft, spaced bearings mounted on the boom and receiving the shipper shaft, a sprocket wheel fixed to the shipper shaft between the bearings thereof, a sleeve shaft mounted on the pivot shaft of the boom, asprocket wheel fixed to the sleeve shaft, a sprocket chain trained over the sprocket wheels, and means for rotating the sleeve shaft in either direction.

4. An excavator crane comprising a platform having a boom foot socket, a boom having a foot, a shaft pivotally connecting the boom to the boom foot socket, a shipper shaft,

spaced bearings mounted on the boom and receiving the shipper shaft, a sprocket wheel fixed to the shipper shaft between the bearings thereof, a sleeve shaft mounted on the pivot shaft of the boom, a sprocket wheel the sleeve shaft, a sprocket chain trained over the sprocket wheels, and means for rotating the sleeve shaft in either direction, and including a digging drum having a sprocket wheel, bracket arms mounted on the pivot shaft of the boom, a shaft mounted on said bracket arms, a sprocket wheel mounted on said last mentioned shaft, a sprocket chain trained over said last mentioned sprocket wheel and over the sprocket wheel of the digging drum, means for swinging said arms to tension said last mentioned sprocket chain, and ears between the shaft mounted on the bracl ret arms and the sleeve shaft.

5. An excavator crane comprising a platform having a boom foot socket, a boom having a foot, a shaft pivotally connecting the boom to the boom foot socket, a shipper shaft, spaced bearings mounted on the boom and receiving the shipper shaft, asprocket wheel fixed to the shipper shaft between the bearings thereof, a sleeve shaft mounted on the pivot shaft of the boom, a sprocket wheel fixed to the sleeve shaft, a sprocket chain trained over the sprocket wheels, and means for rotating the sleeve shaft in either direction'and including'a digging drum having a sprocket wheel, bracket arms mounted on the pivot shaft of the boom, a shaft mounted on said bracket arms, a sprocket wheel mounted on said last mentioned shaft, a sprocket chain trained over said last mentioned sprocket wheel, and over the sprocket wheel of the digging drum, means for swinging said arms to tension said last mentioned sprocket chains, and gears between the shaft mounted on the bracket arms and the sleeve shaft, said means for swinging the bracket arms to tension the associated sprocket chain including screws pivotally connected to the bracket arms and adjustably connected to the bracket arms and adjustably connected to the platform.

6. An excavator crane comprising a plat form, a boom mounted on the platform, a dipper stick mounted on the boom, crowding mechanism mounted on the boom and o eratively associated with the dipper stick, a oist line associated with the boom and operatively associated with the dipper stick, a digging drum, means operated from the digging drum and driving said crowding mechanism, a hoisting drum operatively associated with the hoist line, a boom hoist drum, means controlled by the boom hoist drum for raising and lowering the boom, a single drum shaft mounted on the platform and supportin the digging drum, the hoisting drum and the boom hoist drum and means for independently or simultaneously actuating said drums from said shaft.

7 An excavator crane comprising a platform, a boom mounted on the platform, a dipper stick mounted on the boom, crowding mechanism mounted on the boom and operatively associated with the dipper stick, a hoist line associated with the boom and op.- eratively associated with the dipper stick, a digging drum, means operated fromthe digging drum and driving said crowding mechanism, a hoisting drum operativel associated with the hoist line, a boom oist drum, means controlled by the boom hoist drum for raising and lowering the boom, a single drum shaft mounted on the platform and supporting the digging drum, the hoisting drum and the boom hoist drum, means for constantly rotating the single drum shaft, and independent means for actuating each of the drums from the drum shaft. 4

8. A drive for the shipper shaft of an excavator crane including a platform and a boom on the platform and on which the shipper shaft is mounted and comprising a digging sprocket wheel, a shaft, a sprocket wheel fixed to said shaft, a chain extending around said sprocket wheels,

on said shaft bracket arms support- 1 shaft, and; ch

tween the sleeve shaft and the shipper shaft.

hoist lineassociated with the boom and "is i ing said-shaft for movement about the axis of swin'g of the boom, means for adjusting said bracket arms and holding them in adj usted position to tension said rocket chain,- 5 and means for takingmotion-Zom said shaft and transmitting motion through the axis of swin of the boom to the shipper shaft. 9. A rive forthe shipper shaft of an excavator' crane including aplatform and a boom on the platform and on which the shipper-shaft is mounted and comprising a digg'sprocket wheel, a shaft,,a sprocket wheel. ed to said shaft, a chain extending around said rocket wheels, bracket arms supporting saidshaft for-movement about the axis of swing ofthe boom, meansfor adjusting said bracket arms and holding them in adslightly deflected traveling from the hoisting drum out over the boom, and a double chain from thegging drum and exerted along shipiper shaft drive means actuated the platform in ofl'set relation to the boom signatures. HOLGER L. MITCHELL.

ROLF LJUNGKULL.

justedposition to tension said sprocket chain,

and means for transmitting motion fromthe,

sleeve shaft mounted for rotation about the axis of;the boom foot and geared tosaid ain and sprocket gearingbe- 10. excavator crane comprising a platform, a boommounted on the' platform, a dippler stick mounted on theboom, crowding mec anism'mounted' on theboom and 0 eratively associated with'the dipper stic a eratively connected to'thedipper stick, digging and hoisting drums supported on the 1 platform for rotation about a common axis, saidhoisting drum being connected with said 1y of the platform in ap roximate fore and aft alinement with the m whereb the hoisting line will not be excessively de ected boom,

.means extending between the crowding mechanism'and the shaft to the shipper shaft, and including a hoisting line and being arran ed transversein extending from the hoisting drum to the chain and sprocket gearing drive excavator comprising a platform,

operativeliualzssociated with the dipper stick,

said crow g per shaft, spaced bearings on the boom for the ship er shaft andgearing between the shipper aft and the dipper stick, a hoisting line extendin out over the boom and con-t lg nectedto the ipper stick, digging and hoisting drums supported for rotation on said platform and about acommon axis, said oisting linebeing connected to said hoisting drum, said hoisting" drum-being arranged in approximatefore and aft alinement with the boom whereby said hoisting line will be but .i.

mechanism including a ship- 

